Group III-nitride (“III-N”) compound semiconductor materials, including GaN, advantageously possess a wide band gap (or bandgap), a high breakdown voltage, and a large thermal conductivity under very high power levels (100 kW to 1 MW) and temperatures exceeding 250° C. without requiring liquid cooling. In addition, a wide-bandgap heterostructure system, e.g., incorporating a AlGaN/GaN heterostructure enhanced by spontaneous and piezoelectric polarization effects, yields a two-dimensional electron gas (2DEG) channel with a high sheet charge concentration and high electron mobility (associated with high current density). As such, Group III-nitride semiconductor materials, e.g., the heterostructure system, are favored candidates for fabricating power semiconductor devices.
Power semiconductor devices include two categories: 1) transistors (used as switches) and 2) rectifiers (converting alternating current (AC) to direct current (DC)). Transistors and rectifiers are essential components in high voltage power electronics applications including, e.g., switching-mode power supplies, power converters, high current/voltage driving circuits, power factor correction circuits, etc. As such, low on-resistance (RON) and high off-state breakdown voltage (BV) are desirable transistor/rectifier features.
Conventional AlGaN/GaN high electron mobility transistors (HEMTs) and lateral field-effect rectifiers (L-FERs) cannot simultaneously achieve high BV (or channel punch-through immunity) and low RON because improving channel punch-through immunity of such devices, i.e., by increasing Schottky contact length (>1 μm), increases RON. Further, operation of a conventional enhancement/depletion mode HEMT can fail due to high current flow caused (1) when a drain electrode of the HEMT is negatively biased, i.e., during an accidental reverse battery connection in an electric vehicle application, during a switch-mode Class-S amplifier application resulting in fly-back, etc; and/or (2) when a gate electrode of the HEMT experiences a high positive DC or pulse voltage. Furthermore, operation of a conventional rectifier, i.e., a Schottky barrier diode (SBD), an L-FER, etc. can fail due to an increase in the forward bias voltage at the anode of the rectifier, which can increase on-state current that can lead to device failure.
The above-described deficiencies of today's power semiconductor devices and related technologies are merely intended to provide an overview of some of the problems of conventional technology, and are not intended to be exhaustive. Other problems with the state of the art, and corresponding benefits of some of the various non-limiting embodiments described herein, may become further apparent upon review of the following detailed description.